Farmers trade cowpea seeds with friends and family

Flickr/IITA Image Library

[NAIROBI] African farmers who lose their seeds in floods and droughts could restore their crop biodiversity quicker by trading local seed varieties at markets and through informal social links than by receiving seeds from aid agencies, a study suggests.

The genetic diversity of crops allows plant populations to adapt to changing environments and provides the raw materials for crop improvement programmes. It is crucial for ensuring food security through the traditional African cropping system.

But, after natural disasters, relief efforts may fail to provide a sufficiently diverse range of seeds.

"Disasters, as well as subsequent relief and recovery activities, have significant impacts on agro-biodiversity, including diversity of crops and their varieties that may exist in a farming system," said Morag Ferguson, a researcher at the Nairobi-basedInternational Institute of Tropical Agriculture and the study's lead author.

Aid agencies provide farmers with seeds from formal seed distributors, often from neighbouring countries. But these foreign seeds may fail to restore local biodiversity, putting traditional farming systems that rely on diversity at risk, according to the study published in Disasters (31 May).

The study explored cowpea (Vigna unguiculata) diversity in Gaza Province, Mozambique, following the 2000 floods and 2001 droughts, which caused some farmers to lose all their seed.

Researchers found a narrowing of the genetic base, with fewer rare alleles (alternative forms of a gene), although most of the biodiversity was regained within two and a half years.

Most farmers obtained new seeds from local markets, but these were mostly from the relief efforts and did little to restore diversity. But almost a third got them from friends and relatives in areas without floods.

"It appears that diversity was regained primarily through social networking in the form of loans or gifts of seed from friends and relatives," Ferguson told SciDev.Net.

The study recommends that future seed distribution efforts target social networks and provide more local seeds at markets.

Shem Wandiga, the director of the UNESCO-associated Centre for Science and Technology Innovation, in Nairobi, advocates storing seeds of important crops to increase genetic diversity after natural disasters.

"To prevent loss of biodiversity, collecting the germplasm of various plants and storing it for future use is the surest way of avoiding the total loss of some species," said Wandiga. But the best way to prevent biodiversity loss, he added, is to create protected areas where human activity and resource exploitation are limited.